Safe autonomous flight is essential for widespread acceptance of aircraft
that must fly close to the ground. We have developed a method
of collision avoidance that can be used in three dimensions in much
the same way as autonomous ground vehicles that navigate over unexplored
terrain. Safe navigation is accomplished by a combination
of online environmental sensing, path planning and collision avoidance.
Here we outline our methodology and report results with an
autonomous helicopter that operates at low elevations in uncharted
environments, some of which are densely populated with obstacles
such as buildings, trees and wires. We have recently completed over
700 successful runs in which the helicopter traveled between coarsely
specified waypoints separated by hundreds of meters, at speeds of up
to 10ms1 at elevations of 511m above ground level. The helicopter
safely avoids large objects such as buildings and trees but also wires
as thin as 6 mm. We believe this represents the first time an air vehicle
has traveled this fast so close to obstacles. The collision avoidance
method learns to avoid obstacles by observing the performance of a
human operator.

Multimedia Key

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Extension

Type

Description

1

Example
1: In this experiment, the helicopter follows
a sequence of waypoints. Obstacles
in the path are trees, wires and
buildings. (7 MB) mov

2

Example
2: A comparison of the effect of setting
a soft ceiling for the planning algorithm. (44 MB) mov